Asphalt mixes, hot and cold, can experience bond loss due to moisture damage, a phenomenon called “debonding” or “stripping.” Debonding in hot mixes has been given more attention by researchers than debonding in cold mixes and seal coats, and there has been no documented methodology to quantify bond loss in seal coats. This report contains a description of a newly developed laboratory test experiment called Seal Coat Debonding Test (SDT) to examine the extent of seal coat susceptibility to moisture damage.

When the test was performed on several emulsion based seal-coat specimens, with asphalt emulsion binder, the nature of the outcome strongly suggested dividing seal coats into three categories according to their degree of vulnerability (DV) to moisture damage. Highly vulnerable seal coats are those that experience a loss of aggregate of more than 20% (based on the weight of the base bitumen and the totally intact aggregate). Moderately vulnerable seal coats lose more than 10% and up to 20%, and low vulnerable seal coats lose up to 10%.

The test is relatively easy to conduct and is considered unique in the sense that no similar tests are currently in use to quantify the amount of bond loss in seal coats. The test is applicable only to seal coats using asphalt emulsion as a binder.